DESCRIPTION: While many recent time series studies have demonstrated associations between particle pollution exposure and hospitalization or mortality, the population at risk has not been well-defined. This is particularly true for cardiovascular outcomes. This project will conduct a study of hospitalizations of persons, aged 66 and older, for cardiovascular and respiratory disease in Birmingham AL, Detroit MI, Minneapolis MN, Philadelphia PA, and Spokane WA to investigate predisposing factors for the adverse effects of particulate air pollution. These specific cities have been chosen, first because daily inhalable particle concentrations have been measured for an extended period and, second because they represent a range of particulate sources, sources of other coincident pollutants and of weather patterns. This study will attempt to define predisposing factors for acute cardiovascular effects associated with particulate air pollution episodes. Hospital admissions data of persons aged 66 and older will be obtained from Medicare records for the period 1984-1993. Air quality data (PM10, SO2, O3, CO) will be obtained from the AIRS system of the Environmental Protection Agency (EPA). Weather data will be obtained from the National Climatic Data Center. The intent is to: 1) confirm the association between PM10 and hospital admissions for heart disease, previously reported, while testing the sensitivity of those associations to specification of weather factors, and co-pollutants; 2) determine whether conditions predisposing to hypoxia are risk factors for ischemia, heart failure, cerebrovascular accidents, and acute respiratory infections, as measured by admissions; 3) determine whether the association with air pollution is limited to persons with a high probability of dying, based on mortality risk scores; and 4) determine whether deaths in hospitals for ischemia that are associated with air pollution are primarily short-stay events. Acute cardiovascular events will be compared to concentrations of particles and other pollutants on the same and previous days, using Poisson time series regression analysis. Acute cardiovascular events on high and low particulate concentration days will further be linked by patient identification in the Medicare records to previous admissions and visited to determine predisposing risk factors for acute response to particle air pollution. This will be analyzed using logistic regression. Mortality risk scores will be computed for each admission to determine whether the increased risk is only among those with a high probability of dying. We expect that this study will define the population at risk for serious, acute, cardiovascular effects attributable to particulate air pollution.